Single-phase induction regulator



April 1953 G. TUBBS 2,637,016

SINGLE-PHASE INDUCTION REGULATOR Filed Dec. 20, 1950 WITNESSES: INVENTOR 5%77VZ LesTerG.Tubbs.

dww/z ATTORN Patented Apr. 28, 1953 SINGLE-PHASE INDUCTION REGULATOR Lester G. Tubbs, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 20, 1950, Serial No. 201,835

6 Claims.

This invention relates to regulators and particularly to single-phase induction regulators used in maintaining a line voltage substantially constant.

When the impedance of a load connected to the secondary winding of an induction regulator decreases, the magnitude of the load current and hence the magnitude of the current in the secondary winding of the regulator increases. Therefore, if only one induction regulator is to be used in conjunction with a load that varies between wide limits, the secondary winding of the induction regulator must so be constructed as to withstand the increased secondary current due to a decrease in the impedance of the load without injury to the winding.

Heretofore, in induction regulators having a two-section secondary winding, the increase in load current was handled by connecting the two sections of the secondary winding in parallel circuit connection. By so connecting the sections of the secondary winding, two current ratings for the secondary winding could be obtained-a low current rating when the two sections were connected in series circuit connection and a higher current rating when the sections were connected in parallel circuit connection. With the sections of the secondary winding connected in series circuit connection, it was possible, for instance, to obtain a current rating of 300 amperes for the secondary winding and a voltage regulation of 10% buck or boost, and with the sections of the secondary winding connected in parallel circuit connection, it was possible to obtain a current rating of 600 amperes for the secondary winding and 5% buck or boost voltage regulation. Oftentimes it is desirable to obtain a current rating for the secondary winding which is intermediate the values that are obtainable when connecting the sections of the secondary winding in series or parallel circuit connection.

Many times, the value of the load current is intermediate the value of the higher and lower current ratings for the secondary winding. On switching to the higher rating or parallel circuit connection, when the load current is at some intermediate value, the per cent voltage regulation is considerably decreased. Frequently, this decreased per cent voltage regulation is not sufficient to maintain the line voltage constant. Therefore, unless such an intermediate current rating for the secondary winding can be obtained with a single induction regulator, another induction regulator capable of withstanding the load current and having a high enough per cent volt- I age regulation will have to be utilized. It is,

therefore, desirable to provide an induction voltage regulator which has more than two current ratings for the secondary winding.

An object of this invention is the provision of an induction voltage regulator having a two-section secondary winding, which sections have taps on them so as to obtain a plurality of current ratings for the secondary winding with a minimum of power loss.

A further object of this invention is to obtain a plurality of current ratings for the secondary winding of an induction voltage regulator with a minimum of power loss in the secondary winding by providing a tapped and sectionalized winding and connecting a portion of each section of the secondary winding in parallel circuit connection with a portion of the other section, the remainder of the secondary winding being in series circuit connection with the said parallel circuit connection.

Other objects of this invention will become apparent from the following description when taken in conjunction with the accompanying drawing, the single figure of which is a diagrammatic representation of apparatus and circuits illustrating an embodiment of this invention.

Referring to the drawing, there is illustrated a regulating system 8 embodying the teachings of this invention. The regulating system 8 comprises a single-phase induction voltage regulator l0 having a rotatable primary winding H and a stationary secondary winding consisting of sections 12a and I22), the regulator It! being electrically connected to a main electrical circuit 13. Switching means M disposed to be manually operated is electrically connected to the secondary winding sections Ma and 12b of the induction regulator It for selectively connecting the sections I2d and I2?) of the secondary winding in a plurality of circuit connections. In order to prevent the operation of the switching means M unless the primary winding ll of the induction regulator it] is in its neutral position to thereby prevent flux produced by the alternating current flowing in the primary winding H from interlinking the secondary winding sections l2a and [22), an interlock means I5 is disposed in operative relation with respect to both the induction regulator It and the switching means Hi. Control means [6 is provided for controlling the rotation of the primary winding H in one direction or the other and for varying the electrical coupling between the primary winding II and the secondary winding sections I 2a and lib so as to maintain the output voltage of the induction regulator substantially constant.

The main electrical circuit !3 comprises line conductors l1 and i8l8 and is connected to a source (not shown) of single-phase energy. The induction regulator I is connected in circuit with line conductors I? and l8l8' in order to compensate for the variations in voltage occurring on the main circuit 93.

The induction regulator I!) as hereinbefore mentioned comprises the primary winding I i disposed on a rotor 19, the primary winding H being connected across the conductors 1 and H3. The secondary winding sections |2a and HI) are disposed to be connected in series circuit relation with the conductors l8 and 18. The secondary winding sections 12a and [2b are provided with taps 29 and 29' and 2i and 2!, respectively, associated with portions 22 and 23, respectively, and disposed for connection to the switching means Hi to control the predetermined connection of the portions 22 and 23, respectively, in the secondary winding circuit.

The switching means [9 is provided in order that a plurality of current ratings may be obtained for the secondary winding of the regulator Hi. This is eiiected by either connecting the secti'ons 2a and 12b of the secondary winding in series circuit relation, parallel circuit relation, or by connecting the portions 22 and 23 in parallel circuit relation with the remaining portions of the sections [2a and i2b being connected in series with this latter parallel circuit connection. The switching means 14 illustrated comprises a plurality of spaced terminals 24, 25, 26, 27, 28, 29, 30 and 31 and a terminal bridging member 32. The terminals 24 and 25 are electrically connected to one end of the section i212 and to the tap 29' of section [2a, respectively, the terminals 2B and 29 being connected to one end of the section 12a and the tap 21 of section i217, respectively. On the other hand, the terminals 26 and 21 are electrically connected to the tap 21 and the tap 29, respectively and the terminals 30 and 3| are connected to the tap and the tap 2 i respectively.

The bridging member 32 is provided to facilitate in the making of the hereinbefore-mentioned circuit connections of the sections l2a and I217 of the secondary winding. The bridging member 32 can be actuated into any one of three positions. In the position shown in the drawing in which the terminals 26 and 21 areelectrically connected to one another and the terminals 30 and 3! are likewise electrically connected to one another by means of the bridging member 32, the portions 22 and 23 of the secondary winding sections 12a and [2b are connected in parallel circuit relation with one another. The remaining portions of the secondary winding sections are connected in series circuit relation with this latter parallel circuit connection. The sections 12a and 12b of the secondary winding may be connected in series circuit relation by actuating the bridging member 32 to the left so as to electrically connect the terminals 23 and 26 to one another and electrically connect the terminals 29 and 39 to one another. The parallel circuit connection of the sections [2a and 12b of the secondary winding may be obtained by actuating the bridging member 32 further to the left so as to electrically connect the terminals 24 and 25 to one another and electrically connect the terminals 28 and 29 to one another.

As hereinbefore mentioned, when the conducting bars 33 and 34 are positioned as shown in the drawing so as to bridge only the terminals 26-21 and 303I, respectively, the portions 22 and 23 0f the secondary winding sections l2a and 12b are connected in parallel circuit relation with one another, the remaining portions of the secondary windings sections We and i219 being connected in series circuit relation with this latter parallel circuit connection. The parallel portion of this circuit extends from the tap 2! of section 121) to tap 2B of section 12a. Thus one side of the parallel circuit extends from tap 2!, through terminal 3!, conducting bar 35, terminal 39, terminal 25, tap 2c, and the portion 22 of secondary winding section 12a to tap 22 and the other side of the parallel circuit extends from tap 21 of section 521) through portion 23 of the secondary winding section 121), tap 2;, terminal 26, conducting bar 33, and terminal 2'5 to the tap 29. The series circuit thus extends from the line conductor [8, through a portion of the secondary winding section 21) to the terminal 2 l, the parallel connected sections 22 and 23, tap 23, the remaining portion of Winding section 52a and line conductor it.

The bridging member 32 comprises conducting bars 33 and 34, associated with terminals 2 2-252321 and 232933-3 i, respectively, these bars being of sufficient length to bridge three of the associated adjacent terminals of the switching means it during a switching operation. For instance, when the conducting bar 33 is actuated to the left from its position as shown in the drawing, it remains in contact engagement with the terminal 2? until after it makes electrical contact with the terminal 25. Likewise the conducting bar 34 remains in contact engagement with the terminal 3i until after it makes electrical contact with the terminal 29. When the conducting bars 33 and 3 bridge terminals 2525 I 2? and 293fi3 I, respectively, they establish low resistance shunting circuits about the portions 22 and 23, respectively. The shunting circuit thus established extends from conductor 18 through a portion of Winding section I211 to the tap 29 and from thence through terminal 21 of the switching device M, conducting bar 33, terminal 29, terminal 23, conducting bar 32, terminal 3%, tap 2| and a part of the winding section I227 to the conductor l8.

When the bridging member 32 is being actuated from one position to another position, the terminals 25, 2B and 2! and the terminals 29, 30 and 31 are only momentarily bridged by the conducting bars 33 and 34, respectively, so as to prevent an interruption of the secondary winding circuit during a switching operation and thereby prevent an interruption of the power supply to the load and undue wear on the contact members of the switching means I4.

When the conducting bars 33 and 34 are further actuated to complete the switching operation and bridge only terminals 2526 and 29-33, respectively, the complete winding sections 12a and 12b are connected in series circuit relation. This circuit extends from the conductor 18 through Winding section 12a, tap 21], terminal 25, conducting bar 33, terminal 2!, and winding section 121) to the conductor 18.

As the bridging member 32 is further actuated to effect another switching operation, the conducting bars 33 24-2523 and 28-29--39, respectively, to es-' tablish low resistance shunting circuits about the secondary winding sections i211 and 12b. The

conductor [3 through terminal 28 of the switchand 34 bridge terminals ing device i4, conducting bar 34, terminals 29 and 26, conducting bar 33 and terminal 24 to the conductor It. Again, it is only when the conducting bars 33 and 34 are being actuated during a switching operation from one position to another so as to obtain a different circuit connection of the sections 12a and i229 that they momentarily bridge the terminals 24, 25 and 2t and the terminals 28, 2d and Eli, respectively, to prevent an open circuit condition.

As the switching operation is continued so that the conducting bars 33 and 34 bridge only terminals i i-25 and 28-29, respectively, the winding sections 12a and iilb are connected in parallel circuit relation. This circuit extends from the conductor i8 through winding section [2a, tap 2G, terminal 25, conducting bar 33 and terminal 24 to conductor i8'- and from the conductor it through terminal 28, conducting bar 34, terminals 29 and 25, tap 2i and Winding section :27) to the conductor l 8'.

During the foregoing described switching operations it is necessary to return the primary winding i! to its neutral position for each switching operation to prevent an excessive flow of current in the shunted portions of the secondary winding sections {2d and 12b. The interlock means i is thus provided to prevent movement of the bridging member 32 unless the primary winding ii is in its neutral position as shown in the drawing. The interlock means [5 comprises two interlock discs 56 and 38 and a cooperating rod member iii. The rod member 40 is provided with notch-engaging members 42 and 44 adjacent the ends thereof disposed for selective engagement with a notch in the interlock disc 36 or one of three spaced notches in the interlock disc 38 as the rod id is selectively pivoted about a fulcrum 46. The interlock disc 36 is mechanically connected to the rotor i9 and is positioned as shown in the drawing, with the notch of the interlock disc 36 disposed to receive the notch-engaging member 42 when the primary winding ii is in its neutral position. When the primary winding l l is rotated through a certain number of degrees of rotation, the in terlock disc 35 is likewise rotated through a corresponding number of degrees of rotation. The interlock disc 38 is mechanically connected to the bridging member 32 and in the embodiment illustrated is provided with a handle Bl disposed for manual operation to effect a simultaneous movement of the interlock disc 38 and a switching operation of the bridging means 32. Thus, the bridging member 32 can be actuated only when the notch-engaging member 54 is out of engagement with the notches in the interlock disc 38. In order that the notch-engaging member M may be normally biased to engage one of the notches formed in the interlock disc 38, a spring biasing means A8 is disposed between the fulcrum M3 and the notch-engaging means 4 1 to apply a force to the rod 40. The spring biasing means 48 in this instance comprises a compression spring til disposed between the rod member to and a stationary wall member 52 to normally bias the rod lil in a clockwise direction about its fulcrum 4t.

In order to disengage the notcheengaging member 44 from one of the notches in the disc 38, it is necessary to rotate the primary winding H to the neutral position as shown in the drawing, and in which the disc 35 is positioned with its notch disposed to receive the notchengaging member 42. With the disc 36 so positioned, the rod 40 may be pivoted by manually applying force to a button 53 in opposition to the biasing force of the spring 50 to thereby cause the notch-engaging member 44 to be actuated out of engagement with one of the notches of the disc 38 and the notch-engaging member 42 into engagement with the notch in the disc 38. It is only when the disc 36 is positioned as shown in the drawing that the rod member 40 may be pivoted in the counter-clockwise direction about the fulcrum 46 to disengage the notch-engaging member 44 from a notch in the disc 38 so that the disc 38 can be actuated to move the bridging member 32 through a switching operation. With the disc 36 in any position but that position corresponding to the neutral position of the primary winding II, it is impossible to pivot the rod member 40 since the notch-engaging member 42 will be prevented by the circumferential surface of the disc 36 from engaging the notch of the disc 36. Therefore, it is impossible for the operator to actuate the bridging member 32 unless he has first returned the primary winding H to its neutral position, which latter operation will hereinafter be described.

hereinfoefore stated, the control means [6 is 'ovided for rotating the rotor H3 in one direcn or th other and for varying the electrical between the primary winding ii and the secoi lary if ing sections Mia and i227 so as main; in the voltage output of the induction and i8 substantially constant. -trol means it comprises relays 5 5, 56 and a motor Ed. The relay 5:; is a beam-type clay and has amovable armature member 82 mechanically connected to a beam memwhich is pivoted about a fulcrum 65. The e armature member 6?. has an operating winding 68 disposed to be energized in response o output of the induction regulator #6 so that eraticn of the relay will be dependent on the output voltage from the induction regulator 9. The relay 5G is also provided with three contact members, a movable contact member Iii connected to one extremity of the beam member and two stationary opposed contact members '52 and i l disposed to be selectively engaged by the movable contact member H3.

The relays 5t; and to comprise operating coils and i3 and contact members 86 and 32, respectively. One end of the operating coil '55 is electrically connected to the stationary contact member and one end of the operating coil electrically connected to the stationary contact member i l. The other ends of the operating coils l5 and it are electrically connected to the line conductor i8. As illustrated the movable contact member id is electrically connected through a switch 98 to the other line conductor so that eith r the contact member 853 or $2 can be selectively actuated to the circuit closing position depending on whether the movable ccntact member ii! is actuated into engagement with 1e stationary contact member 72 or M, respectively.

The motor 66 is provided with an armature 33 and a field winding which is divided into two sections 64 and so which are disposed to be electrically connected across conductors ll and it by the contact members 39 and 232, respectively, when the relays 55 and respectively, are energized in order that the motor 86 may be selectively rotated in either one direction or the other.

, H9 through" as gearing represented by the blbcli 8 d;- so'as'to p10 vide' a l o'wjer speed of retatip for the" rotor 1 s than 'thespeedpfrotation of the armature of the motor-8%. In order that the priniarywinding' l i may he returned to its neutral position'beiorea difier nt circuit connection of thejsecondary inding tions are and a 26 1s obtained; s'tyitchingniearis e14 is'pr'o'vided and. disposed "for ins'rmaroperatioii to selectively controlth'e ener l'ation oftherelays ssandssto selectively efi e'ct the directional' rota tion of the rotor with the neiltral positioii. The switchin means 94 in" this instance conipri'se's switchestfi and ed lsillu rated, tiiswitchc'e is a single pole doublethrow swims hat/iii nei'it'ral position" disposed to be selectively sem ated to e gage cooperat ng stationary w members andfifil. The switches is electfi cally c'onriectedto' lineicon'd ctor n, methane tionary' contac'trnemb'ers this and this" are" electricaily connected tofthe'jc'perating coils races- 1c, respectively, sothat the operating'coil 5 it! or" the coil itmayhe selectiyely{energized was eifectin'g a rotation of the motor Sillin' a predeterh'iin'ed direction to returnfthe' primary Winding H to its neutral position. The switch 931s a single pole single throw switch which is connected in the circuit from the mo /able contact member 1% to the linecondnctor Hi When the sWitoh'QS is in the circuit interruptingposition, it nnllifies the regulating efiect'oftl ie'relay 56. In practicath'e switch 98 is actuatedto the circuit interrupting position before the switch S6 is actuated to a'circuitclosing'positionto control the rotation oithe motor Sill I In operation, the alternating current flowing in the primary Winding l I produces a'magne'tic UK, the amountand-direction of this flux which.

is linked with the secondary winding sections 12d and 28 being dependentupon'th angular'posi tion or the primarywindin'g 'i i. An indn'ced voltage in either direction and of any magnitude within the range of the regulator it maybe.

added to or subtractedfrointhe'voltage'of the circuit constituting'th conductors i1 and iiib'fy' properly adjustin'gthe position of the prii'nary winding i i Inthe drawing, the primary" 'W'iri'ding i i is shown at right 'ahgles td'the' secondary winding sections i261 and 227 so thatthfiririproduced by the alternating current in'the prirdary Winding H does not indiice any voltage in the sections i201, and 12b, and the voltage across' th'e conductors I? and Hi'is unaffectedby-the 'indiic tion regulator IE3) If the primary wincm'gh is rotated froin' neutral position, moreandni'ore of the pri iiux is linked with the secondary Windingsections 52a and l2!) until the Winding H is parallel with the sections lfia and i219 when substantially'all the primary flux is linked with the secondary Winding sections [2d and i211, and a: manners voltage in one direction is induced in the sections We and i219. If the primary winding li is rotated in the oppositedirection from its'heii'tral position, the voltage induced in the sections-12a and i521; will be similarly increased from zero to its'rnaxirn'um alue but in the opposite direction.

The control means lfico'ntrols the directioniof rotation of 'th'e"rotor i9 carryingthe' primary Win ding il as weir asth'e electrical coupling between the'primary winding H and'the secondary' winding*'sections' lid" and: i275, W her'the switch 98 is inthe' closfi position and the switch t it etin tit bi ifi ear 54 1 es response 1 to the voltage across t l'ieco'ridhctors If! and? ['8 toselecti ily'control tli'eenerg izatiori" of relays 58 and 58 and; thereby control the" directionalrotation o'ff t he motor 60 and the positioning' of the'rot'oi" [9 with respect to the secondary Winding" s'e ction sfi'zd and 12b sees to maintain the output yolta ge from the induc't on re'gulat'or 59 substantially constant.

v For nstance, if the output Voltage froth the indiict'iorif regulator 0 rises V aboveth'e regulated value; the" Voltage across the operating coil 68 of the refit-Ly 5 increases, The increased voltage across the operating coil 68 increases thelmag neticp'ull' on the movable, armature 52' eiiectin a piir'otin'g'ofthe' member as about the'fulcrum ofas to: bring the movable contact member it into engagement with the stationary contact rneiiiber Hi. When the contactjinenibers' l9 and 1 3" are in engagemenfl the energizing circuit for the operating coil 1310? the relayltil is est'ahlish'edl" When'the operating'coil i8 is thus energized, the contact, member 82 is actuated to a circuit closing position to thus complete an energizing, circuit'for thefield Winding 85 and thereby efiect' a'r'otation of the armature of the riioto'itil and of the rotor W in a direction and through the prop'ernumber of degrees of rota tion'it o lower theo'utput 'voltage'of the induction r eg illator .i to the r gulated valu e.

ot/ever; iitheout'put voltag'e o'f the induction re'gfilator liifalls below'th'e. regulated value, the Voltageacross'theoperating coil fiii'dectea'sesQ and the contact mem er 19" engages. thestationary contact memberin: With the contactmembe'rs l0 and E2 in engagement the energ-izing'circuit is com plet ed tothepperatingcoilifi of the relay 55; toiactuate the-contact member Bil .to a circuit closing'position to effect the energization of the field Windingv at! The-en'ergization' of? the field Winding 584% will ca se the motor 6n and 'the'rotor mtorotate in a direction and throughthe proper numberv of degrees of rotation to 'rai'sel'th'e' output voltageof the induction-regulator Ii) to it s're'g ulatedvalue. i i r i ,If the load should vary considerably, 'neces sitating a; different circuit connection of the secondary; windingsections Y IZiZ and l2'b'; the

iswitch 98- is .niovedto an open circuit position :discq3'8' is: then manually rotated to" effect ia switching movement-otthe bridging merhber 32.

illustrated in the drawing; the bridging conducting bars 35-2 andflilcare'so positioned as to 'electrica'lly connect the terminals 2ficand 21 together and electrically connect the" terminals 39* id"3lto'g'ether. With the bridging member this positiom the" portions 22 and 23:01" th'" secondary-"winding are connected in'para'llel c chit relatiohwitheach-other and the 'remainseries circuit relation therewith. The magnitude of the load will determine whether it is necessary to actuate the bridging member 32 further to the left so as to obtain either a series or a parallel circuit connection of the sections I21: and i222. If the load current rises to a magnitude above the current rating of the secondary winding sections !2a and l2b when the conducting bar 33 is bridging the terminals 26-21, the bridging member should be actuated to the left so that the conducting bar 33 bridges the terminals E l-25, thus connecting the secondary winding sections We and I212 in parallel circuit relation. If, however, the change in the load current is a decrease instead of an increase the bridging member 32 may be actuated to the left so that the conducting bar 33 bridges the terminals 25-26 thus connecting the sections 52a and i'ib in series circuit relation. Such an operation is desirable when it is necessary to obtain an increase in the percent voltage regulation.

Having determined the correct position of the bridging member 32 for the particular load, the switch 9% is positioned in its neutral position and the switch 98 is actuated to the circuit closing position, thus establishing the regulating system 8 with automatic operation to maintain the output voltage of the induction regulator ill substantially constant. The regulating system 3 is maintained in the automatic operating position until the magnitude of the load current varies sufliciently to again necessitate the changing of the tap connections of the secondary winding sections Ho and i219.

The single-phase induction voltage regulator ill embodying the teachings of this invention can handle a load current that fluctuates over a wide range and at the same time a larger percent voltage regulation can be obtained for each value of load current. This large percent voltage regulation can be obtained with a minimum of loss in the secondary winding sections i211 and 1%.

I claim as my invention:

1. In an induction regulator, the combination comprising, a primary winding, a secondary winding consisting of a plurality of sections, each section having a number of taps and being inductively associated with the primary winding, means for varying the electrical coupling between the primary winding and the sections of the secondary winding, and switching means connected to the taps on the secondary winding for connecting a portion or" one of the sections or" the secondary winding in. parallel circuit relationship with a portion of another section of the secondary winding to thereby establish a secondary winding circult that comprises the two parallel connected portions of the secondary winding sections connected in series circuit relationship with the remaining portions of the secondary winding sections.

2. In an induction regulator, the combination comprising, a stationary secondary winding consisting of two sections, each section having a plurality of taps, a movable primary winding inductively associated with the secondary winding, means for moving the primary winding with respect to the secondary winding so as to vary the electrical coupling therebetween, and switching means connected to the taps on the secondary winding for connecting a portion of one of the sections of the secondary winding in parallel circuit relationship with a portion of the other 10 section of the secondary winding to thereby establish a secondary winding circuit that comprises the two parallel connected portions of the secondary winding sections connected in series circuit relationship with the remaining portions of the secondary winding sections.

3. In an induction regulator, the combination comprising, a primary winding having a support therefor, a secondary winding consisting of two sections, each section having a plurality of taps and being inductively associated with the primary winding, means for varying the electrical coupling between the primary winding and the secondary winding, switching means connected to the taps on the secondary winding for connecting a portion of one of the sections of the secondary winding in parallel circuit relationship with a portion of the other section of the secondary winding to thereby establish a secondary winding circuit that comprises the two parallel connected portions of the secondary winding sections connected in series ci cuit relationship with the remaining portions of the secondary winding sections, and interlock means connected to the switching means and to the support for the primary winding disposed to prevent operation of the switching means while there is electrical coupling between the primary winding and the secondary winding.

4. In an induction regulator, the combination comprising, a stationary secondary winding consisting of two sections, each section having a plurality of taps. a movable primary winding having a support and being inductively associated with the secondary winding, means for moving the primary winding with respect to the secondary windin so as to vary the electrical coupling therebetween, switching means for connecting a portion of one of the sections of the secondary winding in parallel circuit relationship with a portion of the oher section of the secondary winding to thereby establish a secondary winding circuit that comprises the two parallel connected portions of the secondary winding sections connected in series circuit relationship with the remaining portions of the secondary winding sections, said switching means comprising two sets of taps, one set being connected to one of the said portions of the secondary winding and the other set being connected to the other portion, conducting means disposed to be actuated to interconnect each of the two sets of taps, and interlock means connected to the conducting means and to the support for the primary winding disposed to prevent the operation of the conducting means while there is electrical coupling between the primary winding and the secondary winding.

5. In an induction regulator, the combination comprising, a stationary secondary winding consisting of two sections, each section having a plurality of taps, a movable primary winding inductively associated with the secondary winding, means for moving the primary winding with respect to the secondary winding so as to vary the electrical coupling therebetween, and switching means disposed to interconnect the taps on the secondary winding and selectively connect the two sections of the secondary winding in either series circuit relationship, parallel circuit relationship, and so that a portion of one of the sections or" the secondary winding is connected in parallel circuit relationship with a portion of the other section of the secondary winding, to thereby establish a secondary winding circuit that comprises the two parallel connected portions of it the secondary winding sections connected in series circuit relationship with the remaining portions of the secondary winding sections.

6. In an induction regulator, the combination comprising, a stationary secondary winding consisting of two sections, each section having a plurality of taps. a movable primary winding having a support and being inductively associated with the secondary winding, means for moving the primary winding with respect to the secondary winding so as to vary the electrical coupling therebetween, switching means disposed to interconnect the taps on the secondary winding and selectively connect the two sections of the secondary winding in either series circuit relationship, parallel circuit relationship, and so that a portion of one of the sections of the secondary winding is connected in parallel circuit relationship with a portion of the other section of the secondary winding to thereby establish a second- 20 10 the secondary winding.

LESTER G. TUBES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,053,110 Ritchter Feb. 11, 1913 2,157,814 Bolte May 9, 1939 2,355,998 Palme Aug. 15, 1944 

